.beta.-Chloroalanine is an amino acid having physiological activity and is an extremely useful compound as a synthesis intermediate not only for cystein, a sulfur-containing amino acid, but also for certain pharmaceutically valuable compounds and the like. Due to lack of industrially advantageous preparation processes, .beta.-chloroalanine has not yet been utilized fully. Among known synthesis processes of .beta.-chloroalanine, there may be mentioned to esterify serine, followed by chlorination and hydrolysis (J. L. Wood, and L. van Middlesworth, J. Bio. Chem., Vol. 179, Page 529, 1949); and to chlorinate and decompose a cystein derivative in an organic solvent by reacting the derivative with chlorine (H. Baganz and G. Dransch, Chem. Ber. Vol. 93, Page 782, 1960). However, these processes are not suitable for their applications in an industrial scale because both processes require very costly starting materials.
On the other hand, it has also been known to prepare .beta.-chloroalanine by reacting sodium aziridine-2-carboxylate with hydrogen chloride (K. D. Gundermann, G. Holtmann, H. J. Rose, and H. Schulze, Chem. Ber., Vol. 93, Page 1632, 1960). The above process however requires extraordinarily excessive hydrogen chloride upon carrying out the reaction. Furthermore, in order to separate the resultant sodium chloride from a mixture of .beta.-chloroalanine hydrochloride and .alpha.-chloro-.beta.-alanine hydrochloride which is a by-product, it is necessary to add a large amount of ethanol to the reaction mixture to extract the intended product and by-product. It is also required to treat the thus-obtained extract of .beta.-chloroalanine hydrochloride and .alpha.-chloro-.beta.-alanine hydrochloride with ammonia, to add water to the thus-treated extract so as to crystallize .beta.-chloroalanine and then to isolate same. The above process is not fully considered to be an advantageous preparation process from the industrial standpoint because, despite of the adoption of complex steps, the yield of isolated .beta.-chloroalanine is as low as 10% and its isolation steps are extremely cumbersome.